Composition (e. g. ink or varnish) which can undergo cationic and/or radical polymerization and/or crosslinking by irradiation, based on an organic matrix, a silicone diluent and a photoinitiator

Abstract

The invention aims at improving such compositions by proposing a non-toxic diluent harmless to reactivity and by making these compositions translucent, free from metallic impurities and capable of constituting light-polymerisable varnish with good properties of ductility for leveling and surface coating. This aim is achieved by the invention which proposes a composition comprising an organic polymerisable matrix A, containing cyclo-aliphatic epoxide resins or not, acrylates, alkenyl-ethers or polyols, a silicon diluent B with viscosity less than 100 MPa's, a radical and / or cationic (onium salt) photoinitiator C, optionally a light-sensitising material D, a pigment E and another additive F; provided that when A is a cyclo-aliphatic epoxide resin, B has a metal concentration not more than 100 ppm. The invention also concerns the use of the silicon diluent B for preparing a composition crosslinkable by cationic and / or radical process, under UV radiation, in the presence of a photoinitiator (ink or varnish).

Description

BACKGROUND OF THE INVENTION(1) Field of the InventionThe field of the invention is that of photopolymer systems which can be crosslinked and / or polymerized by irradiation, and in particular by UV irradiation or by a beam of electrons, and which can be used in particular to form coatings, such as inks or varnishes.These compositions are of the type comprising an organic matrix whose constituents bear functions that are reactive in polymerization / crosslinking, as well as a photoinitiator which, after absorbing energy, for example UV energy, releases a strong acid: H+ (cationic route) or a free radical (radical route). Cationic photoinitiators thus allow the initiation and propagation of cationic chain polymerizations, whereas radical photoinitiators (PIs) allow the triggering of chain polymerizations by formation of free radicals.In certain applications of coatings or inks (or even of dark varnishes), additives are used, such as pigments, which are capable of appreciably increasing th...

AI Technical Summary

Benefits of technology

Apart from the case in which the matrix A comprises compounds bearing reactive functions frA of the cycloaliphatic expoxide type, the choice of the silicone B as diluent for the composition is of a nature to solve the problems of viscosity in dark inks and varnishes, and of flexibility, spreading or sliding in clear varnishes that can undergo cationic and / or radical photopolymerization, under UV.

The filtration step (e) makes it possible, where necessary, to remove all trace of turbidity from the functionalized silicone oil obtained. Moreover, the heterogeneous catalytic composition can be recovered and then reused, without regeneration being needed, with or without washing, and without any substantial decrease in its performance levels being detected.

Problems solved by technology

The drawback of compositions of this type is their turbid, coloured, and thus non-transparent appearance.

They moreover contain a significant amount of metal, which is not foreign to the problem of absence of translucency and transparency and, what is more, is liable to disrupt the polymerization mechanism.

Such concentrations are not of a nature to promote the use of MEME, since this additive cannot be predominant in the formulation, since it would otherwise make the polymer / reticulate unsuitable for the applications for which it is intended (e.g. antiadhesive paper coating, varnish, inks).

What is more, the crosslinked products obtained from such MEME / CY 179 mixtures suffer from the major drawback of being brittle, which is unacceptable in a good many applications.

The unavoidable conclusion is that the prior art does not suitably satisfy the specifications expected of compositions that can be polymerized and / or crosslinked by irradiation, such as those intended for ink and varnish applications.

In particular, the prior art does not disclose, or even suggest, means (diluents) for controlling the viscosity of photopolymerizable pigmented inks which are not toxic and which do not have a harmful effect on the reactivity of the composition.

It should also be noted that the prior art does not provide a satisfactory solution as regards, on the one hand, the problems of transparency and translucency, and, on the other hand, the presence of metal impurities, in the photopolymerizable compositions under consideration.

Finally, the prior art presents an even greater dearth in the case of polymerization reactive functions which are not epoxy but, for example, either alkenyl ether (e.g. vinyl ether)—via the cationic route—, or acrylate or hydroxyl—via the radical route.

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